Horizontal splitting of tasks within a homogenous pool of virtual machines

ABSTRACT

Horizontal splitting of tasks within a homogenous pool of virtual machines. A primary virtual machine is provided to service requests from a request source during a session. The primary virtual machine services requests having a first priority received during the session. A secondary virtual machine is provided to service requests from the request source during the session. The secondary virtual machine services requests having a second priority received during the session. The first virtual machine and the second virtual machine run on a single physical computing platform.

CLAIM OF PRIORITY

This application claims the benefit of U.S. Provisional Patent Application 61/421,989, entitled “Methods and Systems for making effective use of system resources in an on-demand environment,” by Vijayanth Devadhar, et al., filed Dec. 10, 2010, the entire contents of which are incorporated herein by reference.

COPYRIGHT NOTICE

A portion of the disclosure of this patent document contains material that is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in the Patent and Trademark Office patent file or records, but otherwise reserves all copyright rights whatsoever.

TECHNICAL FIELD

Embodiments relate to techniques for task distribution in an environment having virtual machines. More particularly, embodiments relate to a horizontal distribution strategy that may be used in an environment having multiple virtual machines.

BACKGROUND

Systems that service incoming requests have various mechanisms to respond to requests in an efficient manner. For example, load-balancing strategies have been developed to distribute requests. Other strategies have also been developed. However, these strategies typically focus on request quantities or request sources, which provide an improved, but not optimal result.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention are illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings in which like reference numerals refer to similar elements.

FIG. 1 is a block diagram of one embodiment of a networked system of request sources and application servers that my service requests.

FIG. 2 is a block diagram of one embodiment of an application server having one or more processors.

FIG. 3 is a flow diagram of one embodiment of a technique for utilizing a primary virtual machine and a secondary virtual machine.

FIG. 4 illustrates a block diagram of an environment where an on-demand database service might be used.

FIG. 5 is a block diagram of an embodiment of a multitenant environment.

DETAILED DESCRIPTION

In the following description, numerous specific details are set forth. However, embodiments of the invention may be practiced without these specific details. In other instances, well-known circuits, structures and techniques have not been shown in detail in order not to obscure the understanding of this description.

Techniques described herein may be utilized to provide automatic lifecycle management (e.g., startup, teardown) of multiple virtual machines (e.g., JAVA Virtual Machines, or JVMs) on a single server machine (e.g., an application server, or app server), and the ease of configuration of services that determines which virtual machine the service runs on.

In one embodiment, a secondary app server virtual machine is provided on the same physical computing device as a primary app server. The secondary app server may be used for background jobs. In one embodiment, the secondary app server is run by one or more specified processor cores to prioritize certain types of requests. This may be accomplished by using LINUX utilities, for example, and may allow prioritization of real time requests over background jobs.

FIG. 1 is a block diagram of one embodiment of a networked system of request sources and application servers that may service requests. The example of FIG. 1 provides an example with two request sources, one load balancer and two application servers; however, any number of request sources, load balancers and application servers can be supported using the techniques described herein.

Network 100 may be any type of network that provides connections between request sources 110 and 120 and application servers 160 and 170. Network 100 can be, for example, the Internet, a local area network (LAN), and/or any combination of networks and subnetworks. Request sources 110 and 120 operate to request services and/or resources from application servers 160 and 170. Request sources 110 and 120 can be, for example, computer systems running browser applications that allow a user thereof to interact with application servers 160 and 170. Load balancer 140 may operate to distribute requests from the request sources to the application servers in order to more efficiently utilize the resources provided by the application servers.

Application servers 160 and 170 include one or more processor cores that support execution of virtual machines that may be utilized in servicing requests from request sources 110 and 120. Application servers 160 and 170 function to provide primary and secondary virtual machines as described herein to service requests from request sources 110 and 120.

FIG. 2 is a block diagram of one embodiment of an application server having one or more processors. Alternative application servers may include more, fewer and/or different components.

Application server 200 includes bus 205 or other communication device to communicate information, and processor 210 coupled to bus 205 that may process information. While application server 200 is illustrated with a single processor, application server 200 may include multiple processors and/or co-processors. Application server 200 further may include random access memory (RAM) or other dynamic storage device 220 (referred to as main memory), coupled to bus 205 and may store information and instructions that may be executed by processor 210. Main memory 220 may also be used to store temporary variables or other intermediate information during execution of instructions by processor 210.

One or more processors 210 support operation of multiple virtual machines as discussed herein. One or more processors 210 may further each include one or more processing cores. In one embodiment, individual processor cores may be assigned to virtual machines.

Application server 200 may also include read only memory (ROM) and/or other static storage device 230 coupled to bus 205 that may store static information and instructions for processor 210. Data storage device 240 may be coupled to bus 205 to store information and instructions. Data storage device 240 such as a magnetic disk or optical disc and corresponding drive may be coupled to application server 200.

Application server 200 may also be coupled via bus 205 to display device 250, such as a cathode ray tube (CRT) or liquid crystal display (LCD), to display information to a user. Alphanumeric input device 260, including alphanumeric and other keys, may be coupled to bus 205 to communicate information and command selections to processor 210. Another type of user input device is cursor control 270, such as a mouse, a trackball, or cursor direction keys to communicate direction information and command selections to processor 210 and to control cursor movement on display 250.

Application server 200 further may include network interface(s) 280 to provide access to a network, such as a local area network. Network interface(s) 280 may include, for example, a wireless network interface having antenna 285, which may represent one or more antenna(e). Network interface(s) 280 may also include, for example, a wired network interface to communicate with remote devices via network cable 287, which may be, for example, an Ethernet cable, a coaxial cable, a fiber optic cable, a serial cable, or a parallel cable.

Instructions are provided to memory from a storage device, such as magnetic disk, a read-only memory (ROM) integrated circuit, CD-ROM, DVD, via a remote connection (e.g., over a network via network interface 280) that is either wired or wireless, etc. In alternative embodiments, hard-wired circuitry can be used in place of or in combination with software instructions. Thus, execution of sequences of instructions is not limited to any specific combination of hardware circuitry and software instructions.

A computer-readable medium includes any mechanism that provides (i.e., stores) content (e.g., computer executable instructions) in a form readable by an electronic device (e.g., a computer, a personal digital assistant, a cellular telephone). For example, a computer-readable medium includes read only memory (ROM); random access memory (RAM); magnetic disk storage media; optical storage media; flash memory devices; etc.

FIG. 3 is a flow diagram of one embodiment of a technique for utilizing a primary virtual machine and a secondary virtual machine. In one embodiment, the virtual machines are provided in a multitenant database environment. Example embodiments of multitenant database environments are set forth below.

A primary virtual machine is launched, 310. In one embodiment, the primary virtual machine provides a primary application server to service requests received from remote request sources. The remote request sources can be, for example, computing platforms that a user may utilize a browser or other application to access resources provided by the application server(s). The browser may generate requests that are received, and serviced, by the application server(s).

The primary virtual machine launches the secondary virtual machine, 320. The secondary virtual machine may provide a secondary application server. In one embodiment, the secondary application server runs alongside true application servers only (e.g., no capps, indexers, batch servers, etc). In one embodiment, the secondary application server is launched via an appserver startup task on the primary application server. In one embodiment, the primary application server is responsible for killing secondary application server when appropriate (e.g. mbean+JVM shutdown hooks).

In one embodiment, the primary application server starts the secondary application server using current virtual machine arguments and class paths for the primary virtual machine. Certain properties (e.g., settings path, startup log) may be overridden. In one embodiment, the secondary application server is allowed only as many connections as needed.

In one embodiment, the primary application server may monitor the secondary application server and revive the secondary application server if necessary. For robustness in development scenarios, the secondary application server may also monitor the primary application server, and may kill itself when the good primary application dies. For example, if two-way monitoring is implemented with a blocking read on a local socket connection, when it reaches an EOF, the other application has died.

In one embodiment, the secondary application server may be configured with a unique appname for agent proxying. This appname may be configured in a CMS as a miniAppname, for example. In one embodiment, a CMS may model the secondary application server by storing a value for the application port on the application instances that run secondary application server. In one embodiment, an agent may start a core and a core application (e.g., the primary application server) and may start the secondary application server and manage the secondary application server's life cycle. However, in one embodiment, the secondary application server cannot start the core.

In one embodiment, virtual machines are assigned to particular processing cores on the same computing platform, 330. The core assignments may be accomplished by utilizing operating system utilities and commands. In one embodiment, the primary application server is utilized to process real time requests that are received from the request sources and the secondary application server is utilized to process background (or non-real time) requests. Thus, conceptually, this division of processing may be considered horizontal.

As requests are received, they may be evaluated as background or real time and assigned to the appropriate virtual machine and application server, 340. In one embodiment, the primary application server is exposed to realtime requests via the load balancer. As realtime requests come in, they are proxied to the application server port that the primary virtual machine is monitoring.

In one embodiment, services that consume background (e.g., asynchronous) jobs do not run on the primary virtual machine. They are configured to launch on the secondary virtual machine. These services consume scheduled/queued jobs. The secondary virtual machine is not exposed to the load balancer so it will not receive/serve any realtime requests. Once the application server receives the requests, the requests may be serviced, 350.

FIG. 4 illustrates a block diagram of an environment 410 wherein an on-demand database service might be used. Environment 410 may include user systems 412, network 414, system 416, processor system 417, application platform 418, network interface 420, tenant data storage 422, system data storage 424, program code 426, and process space 428. In other embodiments, environment 410 may not have all of the components listed and/or may have other elements instead of, or in addition to, those listed above.

Environment 410 is an environment in which an on-demand database service exists. User system 412 may be any machine or system that is used by a user to access a database user system. For example, any of user systems 412 can be a handheld computing device, a mobile phone, a laptop computer, a work station, and/or a network of computing devices. As illustrated in FIG. 4 (and in more detail in FIG. 5) user systems 412 might interact via a network 414 with an on-demand database service, which is system 416.

An on-demand database service, such as system 416, is a database system that is made available to outside users that do not need to necessarily be concerned with building and/or maintaining the database system, but instead may be available for their use when the users need the database system (e.g., on the demand of the users). Some on-demand database services may store information from one or more tenants stored into tables of a common database image to form a multi-tenant database system (MTS). Accordingly, “on-demand database service 416” and “system 416” will be used interchangeably herein.

A database image may include one or more database objects. A relational database management system (RDMS) or the equivalent may execute storage and retrieval of information against the database object(s). Application platform 418 may be a framework that allows the applications of system 416 to run, such as the hardware and/or software, e.g., the operating system. In an embodiment, on-demand database service 416 may include an application platform 418 that enables creation, managing and executing one or more applications developed by the provider of the on-demand database service, users accessing the on-demand database service via user systems 412, or third party application developers accessing the on-demand database service via user systems 412.

The users of user systems 412 may differ in their respective capacities, and the capacity of a particular user system 412 might be entirely determined by permissions (permission levels) for the current user. For example, where a salesperson is using a particular user system 412 to interact with system 416, that user system has the capacities allotted to that salesperson. However, while an administrator is using that user system to interact with system 416, that user system has the capacities allotted to that administrator.

In systems with a hierarchical role model, users at one permission level may have access to applications, data, and database information accessible by a lower permission level user, but may not have access to certain applications, database information, and data accessible by a user at a higher permission level. Thus, different users will have different capabilities with regard to accessing and modifying application and database information, depending on a user's security or permission level.

Network 414 is any network or combination of networks of devices that communicate with one another. For example, network 414 can be any one or any combination of a LAN (local area network), WAN (wide area network), telephone network, wireless network, point-to-point network, star network, token ring network, hub network, or other appropriate configuration. As the most common type of computer network in current use is a TCP/IP (Transfer Control Protocol and Internet Protocol) network, such as the global internetwork of networks often referred to as the “Internet” with a capital “I,” that network will be used in many of the examples herein. However, it should be understood that the networks that the present invention might use are not so limited, although TCP/IP is a frequently implemented protocol.

User systems 412 might communicate with system 416 using TCP/IP and, at a higher network level, use other common Internet protocols to communicate, such as HTTP, FTP, AFS, WAP, etc. In an example where HTTP is used, user system 412 might include an HTTP client commonly referred to as a “browser” for sending and receiving HTTP messages to and from an HTTP server at system 416. Such an HTTP server might be implemented as the sole network interface between system 416 and network 414, but other techniques might be used as well or instead. In some implementations, the interface between system 416 and network 414 includes load sharing functionality, such as round-robin HTTP request distributors to balance loads and distribute incoming HTTP requests evenly over a plurality of servers. At least as for the users that are accessing that server, each of the plurality of servers has access to the MTS' data; however, other alternative configurations may be used instead.

In one embodiment, system 416, shown in FIG. 4, implements a web-based customer relationship management (CRM) system. For example, in one embodiment, system 416 includes application servers configured to implement and execute CRM software applications as well as provide related data, code, forms, webpages and other information to and from user systems 412 and to store to, and retrieve from, a database system related data, objects, and Webpage content. With a multi-tenant system, data for multiple tenants may be stored in the same physical database object, however, tenant data typically is arranged so that data of one tenant is kept logically separate from that of other tenants so that one tenant does not have access to another tenant's data, unless such data is expressly shared.

In certain embodiments, system 416 implements applications other than, or in addition to, a CRM application. For example, system 416 may provide tenant access to multiple hosted (standard and custom) applications, including a CRM application. User (or third party developer) applications, which may or may not include CRM, may be supported by the application platform 418, which manages creation, storage of the applications into one or more database objects and executing of the applications in a virtual machine in the process space of the system 416.

One arrangement for elements of system 416 is shown in FIG. 4, including a network interface 420, application platform 418, tenant data storage 422 for tenant data 423, system data storage 424 for system data 425 accessible to system 416 and possibly multiple tenants, program code 426 for implementing various functions of system 416, and a process space 428 for executing MTS system processes and tenant-specific processes, such as running applications as part of an application hosting service. Additional processes that may execute on system 416 include database indexing processes.

Several elements in the system shown in FIG. 4 include conventional, well-known elements that are explained only briefly here. For example, each user system 412 could include a desktop personal computer, workstation, laptop, PDA, cell phone, or any wireless access protocol (WAP) enabled device or any other computing device capable of interfacing directly or indirectly to the Internet or other network connection. User system 412 typically runs an HTTP client, e.g., a browsing program, such as Microsoft's Internet Explorer browser, Netscape's Navigator browser, Opera's browser, or a WAP-enabled browser in the case of a cell phone, PDA or other wireless device, or the like, allowing a user (e.g., subscriber of the multi-tenant database system) of user system 412 to access, process and view information, pages and applications available to it from system 416 over network 414.

Each user system 412 also typically includes one or more user interface devices, such as a keyboard, a mouse, trackball, touch pad, touch screen, pen or the like, for interacting with a graphical user interface (GUI) provided by the browser on a display (e.g., a monitor screen, LCD display, etc.) in conjunction with pages, forms, applications and other information provided by system 416 or other systems or servers. For example, the user interface device can be used to access data and applications hosted by system 416, and to perform searches on stored data, and otherwise allow a user to interact with various GUI pages that may be presented to a user. As discussed above, embodiments are suitable for use with the Internet, which refers to a specific global internetwork of networks. However, it should be understood that other networks can be used instead of the Internet, such as an intranet, an extranet, a virtual private network (VPN), a non-TCP/IP based network, any LAN or WAN or the like.

According to one embodiment, each user system 412 and all of its components are operator configurable using applications, such as a browser, including computer code run using a central processing unit such as an Intel Pentium® processor or the like. Similarly, system 416 (and additional instances of an MTS, where more than one is present) and all of their components might be operator configurable using application(s) including computer code to run using a central processing unit such as processor system 417, which may include an Intel Pentium® processor or the like, and/or multiple processor units.

According to one embodiment, each system 416 is configured to provide webpages, forms, applications, data and media content to user (client) systems 412 to support the access by user systems 412 as tenants of system 416. As such, system 416 provides security mechanisms to keep each tenant's data separate unless the data is shared. If more than one MTS is used, they may be located in close proximity to one another (e.g., in a server farm located in a single building or campus), or they may be distributed at locations remote from one another (e.g., one or more servers located in city A and one or more servers located in city B).

As used herein, each MTS could include one or more logically and/or physically connected servers distributed locally or across one or more geographic locations. Additionally, the term “server” is meant to include a computer system, including processing hardware and process space(s), and an associated storage system and database application (e.g., OODBMS or RDBMS) as is well known in the art. It should also be understood that “server system” and “server” are often used interchangeably herein. Similarly, the database object described herein can be implemented as single databases, a distributed database, a collection of distributed databases, a database with redundant online or offline backups or other redundancies, etc., and might include a distributed database or storage network and associated processing intelligence.

FIG. 5 also illustrates environment 410. However, in FIG. 5 elements of system 416 and various interconnections in an embodiment are further illustrated. FIG. 5 shows that user system 412 may include processor system 412A, memory system 412B, input system 412C, and output system 412D. FIG. 5 shows network 414 and system 416. FIG. 5 also shows that system 416 may include tenant data storage 422, tenant data 423, system data storage 424, system data 425, User Interface (UI) 530, Application Program Interface (API) 532, PL/SOQL 534, save routines 536, application setup mechanism 538, applications servers 500 ₁-500 _(N), system process space 502, tenant process spaces 504, tenant management process space 510, tenant storage area 512, user storage 514, and application metadata 516. In other embodiments, environment 410 may not have the same elements as those listed above and/or may have other elements instead of, or in addition to, those listed above.

User system 412, network 414, system 416, tenant data storage 422, and system data storage 424 were discussed above in FIG. 4. Regarding user system 412, processor system 412A may be any combination of one or more processors. Memory system 412B may be any combination of one or more memory devices, short term, and/or long term memory. Input system 412C may be any combination of input devices, such as one or more keyboards, mice, trackballs, scanners, cameras, and/or interfaces to networks. Output system 412D may be any combination of output devices, such as one or more monitors, printers, and/or interfaces to networks. As shown by FIG. 5, system 416 may include a network interface 420 (of FIG. 4) implemented as a set of HTTP application servers 500, an application platform 418, tenant data storage 422, and system data storage 424.

Also shown is system process space 502, including individual tenant process spaces 504 and a tenant management process space 510. Each application server 500 may be configured to tenant data storage 422 and the tenant data 423 therein, and system data storage 424 and the system data 425 therein to serve requests of user systems 412. The tenant data 423 might be divided into individual tenant storage areas 512, which can be either a physical arrangement and/or a logical arrangement of data. Within each tenant storage area 512, user storage 514 and application metadata 516 might be similarly allocated for each user. For example, a copy of a user's most recently used (MRU) items might be stored to user storage 514. Similarly, a copy of MRU items for an entire organization that is a tenant might be stored to tenant storage area 512. A UI 530 provides a user interface and an API 532 provides an application programmer interface to system 416 resident processes to users and/or developers at user systems 412. The tenant data and the system data may be stored in various databases, such as one or more Oracle™ databases.

Application platform 418 includes an application setup mechanism 538 that supports application developers' creation and management of applications, which may be saved as metadata into tenant data storage 422 by save routines 536 for execution by subscribers as one or more tenant process spaces 504 managed by tenant management process 510 for example. Invocations to such applications may be coded using PL/SOQL 534 that provides a programming language style interface extension to API 532. A detailed description of some PL/SOQL language embodiments is discussed in commonly owned co-pending U.S. Provisional Patent Application 40/828,192 entitled, PROGRAMMING LANGUAGE METHOD AND SYSTEM FOR EXTENDING APIS TO EXECUTE IN CONJUNCTION WITH DATABASE APIS, by Craig Weissman, filed Oct. 4, 2006, which is incorporated in its entirety herein for all purposes. Invocations to applications may be detected by one or more system processes, which manages retrieving application metadata 516 for the subscriber making the invocation and executing the metadata as an application in a virtual machine.

Each application server 500 may be communicably coupled to database systems, e.g., having access to system data 425 and tenant data 423, via a different network connection. For example, one application server 500 ₁ might be coupled via the network 414 (e.g., the Internet), another application server 500 _(N-1) might be coupled via a direct network link, and another application server 500 _(N) might be coupled by yet a different network connection. Transfer Control Protocol and Internet Protocol (TCP/IP) are typical protocols for communicating between application servers 500 and the database system. However, it will be apparent to one skilled in the art that other transport protocols may be used to optimize the system depending on the network interconnect used.

In certain embodiments, each application server 500 is configured to handle requests for any user associated with any organization that is a tenant. Because it is desirable to be able to add and remove application servers from the server pool at any time for any reason, there is preferably no server affinity for a user and/or organization to a specific application server 500. In one embodiment, therefore, an interface system implementing a load balancing function (e.g., an F5 Big-IP load balancer) is communicably coupled between the application servers 500 and the user systems 412 to distribute requests to the application servers 500.

In one embodiment, the load balancer uses a least connections algorithm to route user requests to the application servers 500. Other examples of load balancing algorithms, such as round robin and observed response time, also can be used. For example, in certain embodiments, three consecutive requests from the same user could hit three different application servers 500, and three requests from different users could hit the same application server 500. In this manner, system 416 is multi-tenant, wherein system 416 handles storage of, and access to, different objects, data and applications across disparate users and organizations.

As an example of storage, one tenant might be a company that employs a sales force where each salesperson uses system 416 to manage their sales process. Thus, a user might maintain contact data, leads data, customer follow-up data, performance data, goals and progress data, etc., all applicable to that user's personal sales process (e.g., in tenant data storage 422). In an example of a MTS arrangement, since all of the data and the applications to access, view, modify, report, transmit, calculate, etc., can be maintained and accessed by a user system having nothing more than network access, the user can manage his or her sales efforts and cycles from any of many different user systems. For example, if a salesperson is visiting a customer and the customer has Internet access in their lobby, the salesperson can obtain critical updates as to that customer while waiting for the customer to arrive in the lobby.

While each user's data might be separate from other users' data regardless of the employers of each user, some data might be organization-wide data shared or accessible by a plurality of users or all of the users for a given organization that is a tenant. Thus, there might be some data structures managed by system 416 that are allocated at the tenant level while other data structures might be managed at the user level. Because an MTS might support multiple tenants including possible competitors, the MTS should have security protocols that keep data, applications, and application use separate. Also, because many tenants may opt for access to an MTS rather than maintain their own system, redundancy, up-time, and backup are additional functions that may be implemented in the MTS. In addition to user-specific data and tenant specific data, system 416 might also maintain system level data usable by multiple tenants or other data. Such system level data might include industry reports, news, postings, and the like that are sharable among tenants.

In certain embodiments, user systems 412 (which may be client systems) communicate with application servers 500 to request and update system-level and tenant-level data from system 416 that may require sending one or more queries to tenant data storage 422 and/or system data storage 424. System 416 (e.g., an application server 500 in system 416) automatically generates one or more SQL statements (e.g., one or more SQL queries) that are designed to access the desired information. System data storage 424 may generate query plans to access the requested data from the database.

Each database can generally be viewed as a collection of objects, such as a set of logical tables, containing data fitted into predefined categories. A “table” is one representation of a data object, and may be used herein to simplify the conceptual description of objects and custom objects according to the present invention. It should be understood that “table” and “object” may be used interchangeably herein. Each table generally contains one or more data categories logically arranged as columns or fields in a viewable schema.

Each row or record of a table contains an instance of data for each category defined by the fields. For example, a CRM database may include a table that describes a customer with fields for basic contact information such as name, address, phone number, fax number, etc. Another table might describe a purchase order, including fields for information such as customer, product, sale price, date, etc. In some multi-tenant database systems, standard entity tables might be provided for use by all tenants. For CRM database applications, such standard entities might include tables for Account, Contact, Lead, and Opportunity data, each containing pre-defined fields. It should be understood that the word “entity” may also be used interchangeably herein with “object” and “table”.

In some multi-tenant database systems, tenants may be allowed to create and store custom objects, or they may be allowed to customize standard entities or objects, for example by creating custom fields for standard objects, including custom index fields. U.S. patent application Ser. No. 10/817,161, filed Apr. 2, 2004, entitled “Custom Entities and Fields in a Multi-Tenant Database System”, and which is hereby incorporated herein by reference, teaches systems and methods for creating custom objects as well as customizing standard objects in a multi-tenant database system. In certain embodiments, for example, all custom entity data rows are stored in a single multi-tenant physical table, which may contain multiple logical tables per organization. It is transparent to customers that their multiple “tables” are in fact stored in one large table or that their data may be stored in the same table as the data of other customers.

Reference in the specification to “one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. The appearances of the phrase “in one embodiment” in various places in the specification are not necessarily all referring to the same embodiment.

While the invention has been described in terms of several embodiments, those skilled in the art will recognize that the invention is not limited to the embodiments described, but can be practiced with modification and alteration within the spirit and scope of the appended claims. The description is thus to be regarded as illustrative instead of limiting. 

1. A method comprising: providing a primary virtual machine to service requests from a request source during a session, the primary virtual machine to service requests having a first priority received during the session; and providing a secondary virtual machine to service requests from the request source during the session, the secondary virtual machine to service requests having a second priority received during the session, wherein the first virtual machine and the second virtual machine run on a single physical computing platform.
 2. The method of claim 1 wherein the requests having the first priority comprise real time requests.
 3. The method of claim 1 wherein the requests having the second priority comprise background requests.
 4. The method of claim 1 wherein the first virtual machine is supported by a first group of one or more processing cores on the computing platform and the second virtual machine is supported by a second group of one or more processing cores on the computing platform.
 5. The method of claim 1 wherein the computing platform is part of a multitenant database environment, wherein the multitenant database environment stores data for multiple client entities each identified by a tenant identifier (ID) having one of one or more users associated with the tenant ID, wherein users of each of multiple client entities can only access data identified by a tenant ID associated with the respective client entity, and wherein the multitenant database is a hosted database provided by an entity separate from the client entities, and provides on-demand database service to the client entities.
 6. The method of claim 1 wherein the first virtual machine automatically spawns the second virtual machine.
 7. The method of claim 1 wherein the first virtual machine provides a first application server and the second virtual machine provides a second application server.
 8. An article comprising a computer-readable medium having stored thereon instructions that, when executed by one or more processing cores, cause the one or more processing cores to: provide a primary virtual machine to service requests from a request source during a session, the primary virtual machine to service requests having a first priority received during the session; and provide a secondary virtual machine to service requests from the request source during the session, the secondary virtual machine to service requests having a second priority received during the session, wherein the first virtual machine and the second virtual machine run on a single physical computing platform.
 9. The article of claim 8 wherein the requests having the first priority comprise real time requests.
 10. The article of claim 8 wherein the requests having the second priority comprise background requests.
 11. The article of claim 8 wherein the first virtual machine is supported by a first group of one or more processing cores on a computing platform and the second virtual machine is supported by a second group of one or more processing cores on the computing platform.
 12. The article of claim 8 wherein the computing platform is part of a multitenant database environment, wherein the multitenant database environment stores data for multiple client entities each identified by a tenant identifier (ID) having one of one or more users associated with the tenant ID, wherein users of each of multiple client entities can only access data identified by a tenant ID associated with the respective client entity, and wherein the multitenant database is a hosted database provided by an entity separate from the client entities, and provides on-demand database service to the client entities.
 13. The article of claim 8 wherein the first virtual machine automatically spawns the second virtual machine.
 14. The article of claim 8 wherein the first virtual machine provides a first application server and the second virtual machine provides a second application server. 